Airplanes traditionally take off and land with flaps fixed in an extended position. The extended flaps impart high lift characteristics to the aircraft even at low speeds. During take-off, the throttle is opened and the flaps are retained in an extended position for a considerable distance above the runway. The high thrust while at low altitudes create considerable community noise. During an approach, the flaps are extended while on the glide slope angle at a position several miles from the threshold. The extended flaps present high drag as well as imparting high lift and require substantial engine power to effect a constant configuration steady state approach; which creates a high community noise level. In U.S. Pat. No. 2,350,751, there is disclosed an automatic flap control system to adjust the flaps from extended to flight position when a predetermined speed is reached during take-off and to extend the flaps from normal flight position when airspeed falls below a predetermined value. This is essentially a safety device to extend flaps when the airspeed is low, and retract when airspeed is too high.
It is known to utilize a decelerating approach extending the flaps and cutting back on the engine thrust both as a function of time. This has the disadvantage of not allowing for wind direction and velocity near the ground. It was discovered that significant noise reduction benefits may be gained with the control arrangement as disclosed.